Heat Treat oven issues

[Txcwboy]

Ive been building this for a long time. Ran into issues and lost interest. I am trying to get it going again. I made a mistake and cut the grooves on the side bricks all the way to the back. I have to fix those holes. I dont have anymore virgin bricks except what was going to go on top of oven. I was going to cut the back side bricks and replace the middle brick with one brick with the good side inwards. The brick I would use does have grooves on backside. Will that hurt much ? Im out of work and cant buy anymore bricks right now.

The next question- the door design. I will have a 1/4 inch gap between door and front . Do i need to change the design or can this one be modified to work better ?

thanks

Dave